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Type: Artigo de periódico
Title: The enzymology of lysine catabolism in rice seeds - Isolation, characterization, and regulatory properties of a lysine 2-oxoglutarate reductase saccharopine dehydrogenase bifunctional polypeptide
Author: Gaziola, SA
Teixeira, CMG
Lugli, J
Sodek, L
Azevedo, RA
Abstract: In plant, the catabolism of lysine has only been studied in some detail in maize. The enzymes lysine 2-oxoglutarate reductase (also known as lysine alpha-ketoglutarate reductase; LOR) and saccharopine dehydrogenase (SDH), which convert lysine into saccharopine, and saccharopine into glutamic acid and 2-aminoadipate 6-semialdehyde, respectively, were isolated from immature rite seeds and partially purified through a three-step purification procedure involving ammonium sulphate precipitation, and anion-exchange and gel-filtration chromatographies, leading to a final yield of 30% for LOR and 24% for SDH. The molecular masses estimated by gel-filtration chromatography on a Sephacryl S200 column and by native non-denaturing PAGE using Ferguson plots were 203 kDa for both enzymes by gel-filtration and 202 kDa for both enzymes by native non-denaturing PAGE. A second band of LOR and SDH activities on native gels was observed for both enzymes with an estimated molecular mass of 396 kDa, which indicated a multimeric structure. Kinetic studies were consistent with an ordered sequence mechanism for LOR, where 2-oxoglutarate is the first substrate and saccharopine is the last product. The results observed for the LOR/SDH activity ratios during purification, the copurification in all three steps, the molecular masses, the relative mobilities on native non-denaturing gels and the pI estimated for LOR and SDH suggest the existence of a bifunctional polypeptide containing LOR and SDH activities.
Subject: lysine 2-oxoglutarate reductase
saccharopine dehydrogenase
lysine catabolism
Oriza sativa L
Country: EUA
Editor: Wiley-blackwell
Citation: European Journal Of Biochemistry. Wiley-blackwell, v. 247, n. 1, n. 364, n. 371, 1997.
Rights: fechado
Identifier DOI: 10.1111/j.1432-1033.1997.00364.x
Date Issue: 1997
Appears in Collections:Unicamp - Artigos e Outros Documentos

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